Low back pain (LBP) is a leading cause for all physician office visits in the United States.1 Data from other countries (eg, Sweden, the United Kingdom, Scandinavia, and Australia), indicate that LBP is a common problem during pregnancy.2–4 In fact, it is estimated that at least 80% of the population will experience LBP at some point in their lives.1,5 Although most people with LBP symptoms resume normal activities within a few days, some individuals experience progressively worsening LBP, such that their routine activities are limited.6,7 Symptoms of LBP are reported by men and women alike.1 A Swedish survey reports that 66% of women between the ages of 38 and 64 years experience LBP.8 Interestingly, the majority of these women reported that their first episode of LBP occurred during a pregnancy period.9–11 Several other studies also indicate that women with severe LBP during pregnancy are at extremely high risk for developing a new episode of severe LBP during a subsequent pregnancy as well as later in life.4,12,13 Many women report that LBP not only compromises their ability to work during pregnancy but also interferes with activities of daily living.12,14
Interestingly, despite the growing recognition of the importance of LBP during pregnancy, there is a paucity of data regarding the prevalence and severity of this problem in the United States. A search on MEDLINE with key words “low back pain,” “back pain,” “pregnancy,” “abdominal pregnancy,” “pregnancy complication,” “pregnancy maintenance,” and “pregnancy high risk” (1966–March 2004) was conducted. After combining all searches together, 320 articles were identified. We then examined these 320 articles individually and found only one study that focused on the prevalence and severity of LBP during pregnancy. That study was a small-scale retrospective study reporting that 56% of 200 women in a New York hospital suffered from LBP during pregnancy.15 We are unaware of any other studies that are designed to determine the prevalence of LBP during pregnancy among women in the United States. We therefore designed a detailed survey that was administered to pregnant women in New Haven County, Connecticut. The aims of this survey were to determine the prevalence, risk factors, and the impact of LBP in pregnant women who live in New Haven County.
MATERIALS AND METHODS
Respondents to our survey were pregnant women who were attending various antenatal clinics in New Haven County, Connecticut. These clinics included those directed at the indigent population as well as antenatal clinics located at the offices of private obstetricians and midwives. Also, subjects were recruited from various prenatal educational programs sponsored by Yale-New Haven Hospital and The Hospital of Saint Raphael, as well as other private health care organizations in New Haven County.
Data for this study were collected between May 2002 and October 2003.
The questionnaire used in this survey was developed by our study group based on input from prenatal care providers, pregnant women, and a literature search concerning LBP during pregnancy.
The initial version of the questionnaire* consisted of 40 items regarding demographic and baseline characteristics of respondents, recreational habits, history of LBP before and during pregnancy, and the effect of LBP on daily living. During the pilot phase of the study, the questionnaire was pretested by 50 pregnant women and subsequently revised based on analysis of their responses. The final version of the revised questionnaire comprised 36 questions, including the domains listed below:
- Demographic data regarding the participants: age, ethnicity, education, income, number of pregnancies, medications taken, and preexisting medical conditions.
- Respondents’ past experiences with LBP (during previous pregnancies, during menstruation, before pregnancy) and LBP during the current pregnancy.
- Assessment of potential risk factors for LBP.
- For participants who suffered LBP during pregnancy, questions about the location of the pain, its nature, and factors that aggravated the pain.
- Impact of LBP on the activity of daily living as assessed by a validated scale (Daily Disability Index).16 The Daily Disability Index consists of 12 visual analogue scales designated for 12 common daily activities. Scores range from “no difficulty” (score of 0) to “extreme difficulty” (score of 100).
- Time taken off from work, financial impact of LBP in pregnancy, and questions about whether the women disclosed the existence of LBP to their prenatal care providers and the prenatal care providers’ management recommendations.
The survey was also translated into Spanish for use with Spanish-speaking women.
In every location, there was one research assistant who was responsible for distributing and collecting the surveys and answering any questions by potential respondents. All women were instructed to complete the questionnaire only once. Research assistants who attended clinics with significant Hispanic populations spoke Spanish. Research assistants were trained by the principal investigator (S.-M.W.) before the study commenced. All women were notified that anonymity of responses was assured and that the study was approved by the Investigational Committee of Yale-New Haven Hospital and The Hospital of Saint Raphael. Throughout the study period, the principal investigator was in constant contact with the research assistants in each location to direct the survey and address any problems.
Data were analyzed with SPSS 10.1 (SPSS Inc, Chicago, IL). Demographic data are summarized as the mean and standard deviation for continuous data and frequency for categorical data. For each item in the questionnaire, we computed frequency or mean response with standard deviation (SD). Categorical items were analyzed using χ2 analysis. A logistic regression analysis was constructed in which the outcome was the presence or absence of LBP during pregnancy, and predictors included variables selected based on univariate analysis. The final models were limited to significant predictors of LBP. Significance level was accepted at P < .05.
Of the total of 1,131 surveys distributed in the various clinics and activities, 950 surveys were returned (84%). Demographic characteristics of the respondents are shown in Table 1. Respondents were 31.5 ± 4.8 years of age (range 16–46 years), most were in their third trimester (75.1%), and few were in their first trimester (0.4%). The majority of respondents were in their first (61.9%) or second (23.9%) pregnancy. Most of these pregnant women (79.6%) were in good health without any pre-existing medical condition; 19% were taking medications prescribed by their physicians and 2% of respondents were taking over-the-counter medication.
The majority of respondents (68.5%; 95% CI 65–71%) reported having LBP during the current pregnancy. The prevalence of LBP during pregnancy in this sample was not affected by gestational age (P = .56); however, demographic characteristics of this sample were skewed toward women in their third trimester. Of respondents with LBP during pregnancy, 41.4% (95% CI 37–45%) reported that the first occurrence ever of any lower back pain occurred during this pregnancy. The duration of LBP among the respondents ranged from one day to the entire pregnancy. Approximately 4% (95% CI 2–6%) of the women reported constant LBP for 1 week in duration and 10% (95% CI 8–12%) of the women report constant pain for 2 weeks in duration. Please refer to Figure 1 for a detailed description of the duration of pain symptoms.
Pain was reported as occurring in the upper back, the lower back, and the upper and lower back (Table 2). Pain was described as a pulling sensation (20.9%; 95% CI 16–25%), followed by descriptions of shooting sensations (17.1%; 95% CI 13–21%), aching sensations (7.2%; 95% CI 4–10%), and a combination of 2 or more sensations (45.2%; 95% CI 40–50%). Among all women with LBP, 56% (95% CI 51–61%) reported that the standing position aggravated their pain, followed by the sitting position (47.2%; 95% CI 42–52%), bending position (42.4%; 95% CI 37–46%), lying position (36%; 95% CI 31–41%), and walking position (34%; 95% CI 29–39%).
Of women with current LBP, 37% reported LBP before pregnancy, 36.2% reported LBP during a menstrual period, and 21.9% reported LBP during previous pregnancy. The likelihood of a pregnant woman experiencing LBP decreased with age (P = .004). That is, 90% (95% CI 100–80%) of women under the age of 20 years reported LBP, compared with 67% (95% CI 61–71%) of women between the ages of 20 and 30 years, 61% (95% CI 57–65%) of women between 31 and 40 years, and 45% (95% CI 27–63%) of women older than 41 years. In addition, history of LBP without pregnancy (P = .002), LBP during menstruation (P = .01), and LBP during a previous pregnancy (P = .002) also contributes to the development of LBP during current prenancy. A significantly larger proportion of African-American women (89.3%; 95% CI 80–98%) experienced LBP compared with women of other ethnicities (60.5–62.7%; P = .037).
Other potential risk factors in the literature were analyzed and found to be nonsignificant. That is, birth control pill usage (P = .29), history of infertility with hormone therapy (P = .63), caffeine usage during pregnancy (P = .57), smoking during pregnancy (P = .12), physical exercise before pregnancy (P = .18), previous spinal or epidural anesthesia (P = .45), repetitive daily activities (P = .43), prepregnancy body weight (P = .762), and number of pregnancies (P = .20) were not significant predictors of LBP.
We conducted a logistic regression model in which the outcome was the presence or absence of LBP during current pregnancy. We found that LBP during a previous pregnancy (odds ratio 5.7; 95% CI 2.9–11.2), LBP during menstruation (odds ratio 2.5; 95% CI 1.1–6.4), and history of non–pregnancy-related LBP (odds ratio 4; 95% CI 1.7–9.4) were independent predictors for the existence of LBP during pregnancy.
Over half (58%; 95% CI 54–62%) of women with LBP reported sleep disturbances secondary to the pain. The average severity of pain (visual analog scale) reported by the respondents was 45.6 ± 26 (range 8–100; please refer to a detailed distribution presented in Fig. 2). A similar number (57%; 95% CI 53–62%) complained that LBP impaired their daily activities. When assessing the activities of daily living, many women who reported LBP (49%; 95% CI 44–53%) avoided “performing tasks that caused them the greatest difficulty such as climbing stairs” (46.7%; 95% CI 42–51%), “running” (39.7%; 95% CI 35–44%), “heavy work” (28.2%; 95% CI 24–31%), “lifting heavy objects” (28.2%; 95% CI 24–31%), and “participating in exercise” (30.5%; 95% CI 27–35%). The average daily disability index rating was 39.5 ± 22, indicating that respondents with LBP experienced a moderate level of disability related to LBP. Finally, 10.6% (95% CI 8–14%) of all respondents with LBP were forced to take time off from work because of LBP symptoms.
Only 32% (95% CI 28–36%) of women with symptoms of LBP reported these symptoms to their prenatal care providers. Interestingly, these respondents who discussed their symptoms with their care providers reported that 75% (95% CI 71–79%) of prenatal care providers did not recommend any treatment to manage symptoms. The most common suggestions provided by the 25% of prenatal care providers who did make management recommendations were stretching/exercise (10.4%; 95% CI 8–12%), frequent rest (9.8%; 95% CI 8–12%), cold and hot compress (8.7%, 95% CI 7–11%), a supportive belt (3.8%; 95% CI 2–6%), and combinations of therapies from various complementary and allopathic treatments (eg, acetaminophen, massage, acupuncture, chiropractic/osteopathy, aromatherapy, relaxation, herbs, yoga, and Reiki) (13.6%; 95% CI 11–17%).
Our results showed that LBP remains a common problem in women during pregnancy. Based on data collected from the Office of Planning and Development at Yale-New Haven Hospital, the number of births in New Haven County numbered approximately 10,000 for the years 2002 and 2003. We calculate that our survey therefore captured nearly one tenth of the population of pregnant women in New Haven County. Therefore, we estimate that 68.6% (95% CI 65.1–72.1%) of women experience LBP during pregnancy.
We found that LBP can start at any point during pregnancy and that significant predictors for the presence of LBP are age, LBP during menstruation, previous history of back pain, and previous LBP during pregnancy. We also found that the majority of patients do not disclose LBP symptoms to their prenatal care providers and that when LBP is reported, most women report that prenatal care providers do not provide management recommendations for LBP symptoms.
The prevalence of LBP during pregnancy found in our study (68.6%) is similar to the prevalence reported in Scandinavia and Sweden,11,17 but is higher than that reported in the smaller, retrospective, 1987 study.15 Potential reasons for this difference include survey design (cross-sectional versus retrospective, based on recall), the relatively small number of cases in the previous survey study, and regional differences (Brooklyn, New York versus New Haven, Connecticut). In contrast to the existing literature that indicates that LBP mainly occurs primarily during the first 5–7 months of pregnancy,15 we found that LBP may be present at any time during pregnancy. As documented in the literature, we also confirmed that the following variables do not contribute to the development of LBP during pregnancy: use of birth control pills, history of infertility accompanied by hormone therapy, caffeine use, smoking, physical exercise, previous spinal or epidural anesthesia, repetitive daily activities, prepregnancy body weight, and number of pregnancies.18–23 In addition, history of back pain,21 LBP during menstruation, and previous pregnancy-induced LBP21 were significant risk factors for the development of LBP in the current pregnancy.
As the structure of the society changes, LBP in pregnancy extends its negative impact across many areas of women's daily lives, including work, household responsibilities, leisure activities, and sleep. In our sample, nearly 60% of women with LBP indicated that this pain affects their ability to sleep and perform daily activities, and 10.6% of women reported taking time off from work because of LBP. The existing literature supports LBP as the leading reason for taking sick leave for pregnant, working women.14
Our results also show that the pain ranged from mild to severe; on average, respondents reported that LBP was moderate in severity. Nearly 30% of these women with LBP reported that they had to stop at least one daily activity because of LBP. For all other daily activities, they reported mild-to-severe degrees of difficulty because of LBP.
In the United Kingdom and Scandinavia, treatment for LBP during pregnancy frequently includes patient education about LBP, education regarding posture and body mechanics from the first trimester, information about mechanical supports such as type of pillow to use while sleeping, and physiotherapy.24 In the United States, however, most prenatal care clinicians instruct women to accept LBP as a normal part of pregnancy.14 Therefore, it is not surprising that we found that only 32% of the women in our sample had revealed the existence of LBP to their prenatal care providers and that only 25% of these prenatal care providers addressed this problem and provided recommendation to these women.
In conclusion, the data clearly indicate that LBP during pregnancy is a common problem that should not be ignored. At the present time, however, most women fail to report LBP to the prenatal care provider, and most prenatal care providers fail to treat LBP. Future studies should examine the antecedents of prenatal care providers’ failure to treat LBP and examine further the relationship between ethnicity and LBP. In addition, future studies should consider including a wider variety of geographical regions. Finally, the results of this survey underscore the fact that many pregnant women suffer significant pain that is left untreated. This pain impacts not only the individual woman but also adversely affects those she cares for by limiting her daily activities, as well as adversely impacting her work productivity. We call upon researchers to contribute to improving womens’ health through research focused on the prevention and treatment of lower back pain during pregnancy.
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